OK, your goal is going back to trout ponds.
Step one is to remove any damage to your ponds created by the encroaching Maine woods. Are there any trees growing on the dams of your three ponds?
You should never let trees grow on your "sealing" dams, they will almost inevitably cause leaks in the future.
If you currently have some large trees, then there is some debate about removing them now. I say "yes" especially since you have make-up water for small leaks. Others with more knowledge than I have may disagree. Please examine your tree situation and report back if you see cause for concern.
The middle pond sounds like it was designed as a trout run. Excellent for you! There was a member that managed multiple trout runs on his property. (Perhaps even for commercial trout production?) I expect someone else will remember the name so you can search for his discussion topics.
